authors: xiuming zhu 1, song han 1, and aloysius mok 1 1 the department of computer science, the...
TRANSCRIPT
Hardware Challenges and Their Resolution in
Advancing WirelessHARTAuthors: Xiuming Zhu1, Song Han1, and Aloysius Mok1
1The Department of Computer Science, the University of Texas at AustinDeji Chen2, and Mark Nixon2
2Emerson Process ManagementPresenter: Yi-Hung Wei1
Wireless Personal Area Network(WPAN)◦ IEEE 802.15.4◦ ZigBee
Industrial Wireless Network◦ Timing requirement, reliability, security concerns◦ WirelessHART
IEEE 802.15.4 Hardware challenges
Introduction
2003 2004 2005 2006 2007 2008 2009
IEEE 802.15.4 ZigBee WirelessHART FreeScale MC1322
Properties
Real-Time◦ TDMA Technology◦ Centralized Network Management
Reliability◦ Channel Hopping and Channel Blacklisting◦ Mesh Networking
Security◦ Data Integrity on MAC Layer◦ Data Confidentiality on the Network Layer
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
WirelessHART Mesh Network
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Hardware Challenges Development of WirelessHART
◦ Early Prototype◦ Wi-HTest◦ Current System
Future work
Outline
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
TDMA data link layer
Timeslot: 10ms TsTxAckDelay: 1ms
Security mechanism
MAC layer related processing
Authenticate the incoming message
Generate authentication code
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Hardware Challenge: MCU Speed
WirelessHART Slot Timing
Hardware Challenge: Memory Size
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Device Tiny Gateway
Large Gateway
Neighbors 32 12 128
Superframes 16 12 12
Total # of Links
64 50 500
Graphs 32 25 128
Total # of Graph-Neighbor pairs
128 40 1000
Packet Buffers 16 25 500
Total size 6,112 bytes 5,716 bytes 11,6356 bytes
Data Link Layer Minimum Requirement
Device Tiny Gateway
Large Gateway
Sessions 8 30 510
Correspondent Device
1 per Session 1 per Session 16
Transport 2 per Session 30 510
Routes 815 128
Source-Routes 2
Timetables 16 N/A N/A
Total size 1,106 bytes 2,910 bytes 36,508 bytes
Network Layer Minimum Requirement
WirelessHART network is a synchronized network◦ 10ppm drift rate of the MCU clock.◦ The maximum tolerance for drift is 1ms
Synchronize every 50secs between master and slave.
If the chain from time source is longer, the time to sync is shorter.
Hardware Challenge: Clock Precision
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Hardware Challenges Development of WirelessHART
◦ Early Prototype◦ Wi-HTest◦ Current System
Future work
Outline
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
802.15.4 chips available in early day
Early Prototype
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Manufacturer
Chip MCU Max tx Flash RAM
Ember EM250 16bit 24MHz
5dBm 128k 5k
FreeScale MC13214 8bit 40MHz
3dBm 60k 4k
Jennic JN5121 32bit 16MHz
0.4dBm 64k (ROM) 96k
TI-Chipcon
CC2430 8bit 32MHz
0.6dBm 128k 8kb
* J. Song, S. Han, A. K. Mok, D. Chen, M. Lucas, M. Nixon, and W. Pratt, WirelessHART: Applying Wireless Technology in Real-Time Industrial Process Control. Real-Time Technology and Applications Symposium, 2008.* J. Song, S. Han, X. Zhu, A. K. Mok, D. Chen, and M. Nixon, Demo of a Complete WirelessHART Network, ACM SenSys 2008 Demo Session.
Some observations◦ MCU
Only tested with 20ms, 40ms timeslots◦ Software AES engine
MC1321 software AES engine◦ Transmitter
Maximum programmable transmit power is only 3dBm
◦ RAM 4KB is too limited
Early Prototype - resolution
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
10ms
Hardware AES
10dBm
Hardware Challenges Development of WirelessHART
◦ Early Prototype◦ Wi-HTest◦ Current System
Future work
Outline
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Motivation◦ Assure the standard compliance of WirelessHART devices◦ Thorough tests for each layer of WirelessHART stacks are
needed◦ Help vendors avoid expensive product recalls and
technical support costs
Hardware architecture◦ FreeScale MC1320
Physical layer, data link layer ColdFireV1 MCU, 32-bit, 50.33MHz 128KB FLASH 16KB RAM
◦ PC Box Network layer
Wi-HTest
S. Han, J. Song, X. Zhu, A. K. Mok, D. Chen, M. Nixon, W. Pratt, and V. Gondhalekar, Wi-HTest: Compliance Test Suite for Diagnosing Devices in Real-Time WirelessHART Network. Real-Time Technology and Applications Symposium, 2009.
Clock precision◦ ±2.5ppm oscillator as the external clock input◦ The drift is consistent in fixed environment
It is possible to compensate it with software Security computation
◦ CCM algorithm is still expensive Parallel decoding
◦ Pre-compute acknowledgement message Flash Memory Usage
Wi-HTest
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Component
Bootloader
CDC-USB driver
Encryption engine
System library
Operating system
WirelessHART stack
Total
3K 11K 20K 11K 7K 34K 86K
Hardware Challenges Development of WirelessHART
◦ Early Prototype◦ Wi-HTest◦ Current System
Future work
Outline
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Hardware◦ FreeScale MC1322
32-bit 24MHz ARM7 MCU 22mA typical RX current draw 29mA typical TX current draw Extensive sleep mode MAC accelerator Advanced AES hardware engine
Software◦ Complete WirelessHART mesh networking
functionality
Current System
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Current System – cont.
17
10 devices and 1 AP in the system
Devices publish data to GW with different sampling rates (1sec – 8sec)
Retry happens but no packet loss is detected
Hardware Challenges Development of WirelessHART
◦ Early Prototype◦ Wi-HTest◦ Current System
Future work
Outline
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Memory 96K Flash for
WirelessHART stack 24K RAM for the data
section More space for
application layer
Clock High precision Maintains precision
when sleep
Power More sensitive receiver More deeper sleep
mode
Encryption Hardware AES engine
or fast MCU Open AES engine
For future work
Chronicle our work and provide our experience of the system design challenge of WirelessHART◦ Prototype◦ Wi-Htest◦ Complete WirelessHART mesh network
Provide hardware requirement for future industrial wireless embedded network chip
Summary
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Thank You!
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